This invention relates to a micropatterning method using a resist composition designed to lend itself to the lift-off procedure.
The recently increasing degree of integration in semiconductor devices requires a method capable of forming at high precision a pattern having an extremely small line width of less than 0.3 xcexcm. The demand for high integration can be met by increasing resolution or optimizing a resist composition. In connection with the resolution increasing technology, studies have been made on the exposure method having incorporated therein ultrahigh resolution techniques such as modified illumination and phase shifting in compliance with the increased numerical aperture and reduced wavelength. With respect to the resist composition, a change from i-line sensitive novolac compositions to chemical amplification systems is made to match with the reduced wavelength of light sources.
However, with respect to the control of line width, the performance level of positive novolac resist compositions to be exposed to g and i-lines has not been fully reached.
An object of the invention is to provide a novel and improved micropatterning method capable of processing to a controlled line width of less than 0.3 xcexcm while taking advantage of a positive novolac resist composition to be exposed to g and i-lines.
The invention provides a micropatterning method comprising the steps of forming a lift-off resist pattern on a surface of a first layer, forming a second layer over the first layer surface including the resist pattern, removing the resist pattern to partially expose the first layer surface, and etching the exposed area of the first layer. The micropatterning method of the invention has the advantages of a high resolution of 0.3 xcexcm or less and improved dimensional control.